A patient called me early this Sunday complaining of redness and swelling at the site of a tetanus shot from several days earlier. I thought it might be a common immunologic reaction to the vaccine. I told him to come to the office on Monday so I could take a look at the arm. He told me he was skiing near Lake Tahoe. He was worried and so he offered to email me a picture in hopes I might make a diagnosis.
The initial results were quite disappointing.The later that day I called him back and asked him to send another image. The second image was much clearer and it was obvious this was a bruise related to bleeding under the skin at the injection site. The bruise was starting to spread out under the skin which made it appear larger which alarmed the patient. Actually the bruise was fading and flattening out and once reassured my patient returned to the slopes.
What did I tell my patient to get the image to clear up?
First you need to know what kind of camera your patient is using. In this case it was an iPhone3GS. I have an iPhone 3G and so I know that it has a low resolution camera without flash. Also the first image is out of focus and underexposed. It could be out of focus because the camera was too close and couldn't focus or the shutter speed was too slow because the image was taken indoors with out a flash.
I asked the patient to hold the camera further away from his body to allow the camera to focus properly and also to give the image some scale. I also asked him to stand next to a window to allow natural light to be used which rendered the colors more accurately and allowed the camera to use a higher shutter speed to avoid blur.
A camera phone can be used as a diagnostic tool. Remember it is just like any other camera and distance to the subject and lighting are very important. Newer phones are outfitted with more sophisticated imaging so likely image quality will improve. Doctors need to expect more patient generated images in the future.